1. Field of the Invention
The present invention relates to a sheet processing apparatus having a function of performing punching in a sheet.
2. Description of the Related Art
A sheet processing apparatus in which sheets are individually conveyed, and punching is performed in each of the conveyed sheets has been proposed in Japanese Patent Application Laid-Open (Kokai) No. 11-311883 (1999).
In the above-described conventional sheet processing apparatus, however, since conveyed sheets are sequentially punched, position deviation or skew of each sheet with respect to punching means, such as a punch or the like, during a punching operation sometimes causes deviation of a punching position for each sheet. When deviation of a punching position occurs for each sheet, if it is intended to perform binding after performing sheet alignment by superposing a plurality of sheets after punching, the area of punched holes to be used for binding is substantially reduced. As a result, much time is required for a binding operation, or edges are not aligned because a sheet bundle after being bound is oblique with respect to a binder, thereby causing problems in operability and the quality of bound sheets.